You're looking at Less Wrong's discussion board. This includes all posts, including those that haven't been promoted to the front page yet. For more information, see About Less Wrong.

XiXiDu comments on Help me teach Bayes' - Less Wrong Discussion

2 Post author: tomme 11 April 2012 05:56PM

You are viewing a comment permalink. View the original post to see all comments and the full post content.

Comments (19)

You are viewing a single comment's thread. Show more comments above.

Comment author: XiXiDu 11 April 2012 07:13:37PM *  0 points [-]

P(B and A) = P(A) * P(B|A)

To make it clearer, shouldn't this step be = P(B) * P(A|B)?

Also, are middle school pupil in the U.S. familiar with the notation? Maybe one should state it in English instead?

The probability of A if B is known to occur is equal to the probability of A times the probability of B if A is known to occur divided by the probability of B.

ETA

P(A and B) = P(A) * P(B|A)

The probability of A and B to occur at the same time is the same as the probability of A to occur alone times the probability of B to occur under the condition that A is known to occur.